When such a pulley device is manufactured, it is generally equipped with a screw whereof one threaded end is designed to penetrate a tapped orifice formed in a support on which the tensioning roller is provided to be mounted. It is appropriate to avoid, as much as possible, any untimely separation of the screw and the rest of the pulley device between the time of manufacture of the device and the time of its mounting on a support, in particular within the engine compartment of a motor vehicle.
To that end, it is known from US-A-2004/097313 to provide, on a separating sleeve of a tensioning roller, protruding elements obtained by mating the edge of a passage opening with a fastening screw. After being mated, these protruding elements rub against a non-threaded part of the screw, once the latter is already in place within the tensioning roller. This requires providing, in the manufacturing line of such a tensioning roller, a specific step for mating the sleeve to produce the protruding elements, which makes that manufacturing line more complex and expensive. Furthermore, the screw cannot be separated from the sleeve, unless the protruding elements are broken or the threading of the screw is deteriorated.
It is also known from FR-A-2,923,281 to overmold, in the bore of the inner ring of the tensioning roller, a bush that in turn defines a through bore for mounting a fastening screw. In the embodiment of FIGS. 4 and 5 of that document, the bush is provided with a threaded portion seeking to favor the axial retention of the screw. The bush is positioned axially withdrawn relative to the outer ring, such that it does not allow any axial force to be reacted. Furthermore, the threaded portion remains engaged with the thread of the screw during the transport of the tensioning roller, from its manufacture site to its mounting site on a motor vehicle. This results in the risk of breakage of the threaded portion or deformation of the thread of the screw.
Furthermore, it is known from DE-A-198 36 191 to provide, in a housing for receiving the screw, a circlip for axially retaining the rod of the screw, which slides along an outer peripheral groove formed on the shaft of the screw. One drawback of this approach pertains to the retention of the circlip in the inner ring of the rolling bearing, which is not sustainable. Thus, the circuit may itself be lost during use of the device. Another drawback of this approach pertains to its bulk. The head of the screw protrudes from the inner ring of the rolling bearing, which is not desirable during the use of the device in a densely occupied volume, such as the engine compartment of a modern motor vehicle.
The present invention aims more particularly to resolve these drawbacks by proposing a new pulley device whereof the manufacturing is cost-effective and which guarantees effective maintenance of its central screw, including before mounting of the pulley device on a support such as the engine block of a motor vehicle.